1. Field of the Invention
This invention relates in general to drilling and production of oil and gas wells and, in particular, to a design of a slide actuating connector for tubular members.
2. Brief Description of Related Art
A riser is a large diameter pipe used in offshore drilling, production, export, import, mining, and free standing operations to guide the tubing strings, such as drill strings or production strings, from the offshore platform to and from the subsea wellhead and to provide means for circulation of fluid. The tubing string is lowered through the riser. Fluid circulates down from the platform through the tubing string, out through the drill bit, or other sub assembly, and returns to the platform in the space between the inner diameter of the riser and the outer diameter of the tubing string. Environmental forces caused by waves, currents, and the movement of the offshore platform, as well as internal forces caused by the weight of the heavy fluids, all contribute to the substantial loads applied to the riser. Additionally, high pressure risers, utilizing surface blowout preventers, may be exposed to full wellbore pressure. The connection between each successive joint of the riser must be able to withstand such loads.
The prior art makes up the riser pipe or joint connections with bolted flange type connectors or with radially oriented screws that move dogs into and out of engagement with a profile on the riser pipe. Both of these methods require manipulation with a wrench or stud tensioning device, placing personnel in close proximity to the drilling slots for prolonged periods of time, and increasing the danger level of performing the task.
In another prior art embodiment the riser box ends are formed with pockets and locking members positioned within the pockets. The locking members have a profile that mates with a profile on a pin end of the adjacent riser. This riser assembly includes a special cam ring that is actuated by specialty equipment on the platform. The specialty equipment causes the cam to move the locking members into engagement with the profile of the pin end to secure the riser tubulars. These cam assemblies may significantly increase the cost of the platform due to the increased capital costs for the special equipment and more expensive riser members. Therefore, a riser joint that allows for a strong connection that can be rapidly made-up without placing personnel in close proximity to the drilling slots for prolonged periods of time and at a lower capital cost would be desirable.
In still another prior art embodiment, the riser ends are formed with grooves. A collet, or split ring may surround the riser ends, and a sleeve may surround the collet or split ring. The sleeve will have a specially formed thread on an inner diameter that engages with a mating thread on an outer diameter of the collet or split ring. Rotation of the sleeve relative to the collet or split ring radially contracts the collet or split ring to couple the riser ends together. In embodiments utilizing a collet, the collet has inner diameter grooves that will engage the grooves formed on the riser ends. In embodiments utilizing a split ring, the radial contraction of the split ring will cause the grooves on the riser ends to engage. In these embodiments, one riser end will have grooves on an outer diameter portion, and one riser end will have grooves on an inner diameter portion. These riser assemblies require significant manufacturing time to machine complex collet or split ring engaging components. In addition, the strength of the riser may be limited by the strength of the collet member, a member typically formed with a thinner sidewall and subjected to higher rates of fatigue failure. Still further, make-up of these connectors still require worker proximity to rotating machinery. This is a significant worker injury risk. Therefore, a riser joint that allows for a strong connection not limited by an interposed component that can be rapidly made up without complex machined components is desirable.